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Detecting goals with sophisticated technology and reliable gigabit fiber optic connections: French Ligue 1 relies on German goal line technology

Copyright: GoalControl GmbH & MICROSENS

Did the ball touch the goal line? Was it behind or did it just bounce off the line? Previously, these questions were decided in the French Ligue 1 exclusively by referees based on their observations. The situation will change with the 2015/16 season: Following the controversial scene, referee takes a casual look at a watch on their wrist and go ahead and confidently allow the goal - or not - as the case may be.

This is made possible by powerful technology from GoalControl GmbH for which the French league association LFP decided for in May 2015. The network technology connected takes on the crucial role of transmission in the challenging project. Video data have to be transmitted quickly and reliably under extreme conditions and in some cases over long distances via a fiber optic network. The active components for this are supplied by MICROSENS GmbH & Co. KG.

Functionality of GoalControl-4D

The GoalControl-4D system captures all ball movements on the pitch using a total of 14 cameras installed at precisely calculated positions in the stadium. These data are transmitted by a powerful fiber optic network to a central processing unit. Thanks to advanced image recognition, the system takes all movements into account to extract the exact position of the football. As soon as the ball approaches the goal, the system records its exact coordinates. If it really does cross the goal line, this is immediately registered and the central processing unit sends an encrypted optical and acoustic signal to the referee's receiver watch.

Copyright: GoalControl GmbH

Precision down to the last detail

This principle of goal line technology is easy to explain. Optimally matching the individual components requires many series of tests and precise calculations. Seven cameras per goal ensure complete coverage of the entire pitch. Over 500 images are captured, transmitted and processed per second in order to ascertain the exact position of the football to an accuracy of 5 millimetres. In addition, given a shot on goal, within less than 2 milliseconds GoalControl Replay provides all the camera information as video evidence for the viewers. This can only be achieved if all information is transmitted within the shortest time – in all weathers and also from the camera at the other end of the stadium roof.

Convincing glass fiber technology

When it came to the active optical fiber based network components, GoalControl GmbH decided for Microsens GmbH & Co. KG, a pioneer in the field of glass fiber technology. The fully fledged products and the longstanding experience also convinced Dirk Broichhausen, Managing Director of GoalControl GmbH: "Our technology is based on fast and reliable transmission of all data. Microsens supplies us with high-availability components that have already proven their capabilities in Brazil. We are pleased to be able to count upon Microsens as a dependable partner, also for the Ligue 1 project."

Challenge of transmission distances

Together, solutions were also found for special requirements: Networking fourteen cameras under the stadium roof and on the catwalk with the central control unit – this takes several hundred metres of fiber optic cables. According to the standard, the limit values are 275 metres for a 62.5 µm multimode fiber and 550 metres for a fiber with a core diameter of 50 µm. Here GoalControl uses special multimode extenders from Microsens that transmit data over a distance of up to two kilometres without problems, also via multimode fibers. Furthermore, the extreme temperature fluctuations under stadium roofs also pose a huge challenge for optical transmission systems. Here too, the German manufacturer has an alternative on offer: Its robust industrial switches were especially developed for extreme applications and also work reliably and securely at +75 or -40 degrees Celsius. Those who wish to convince themselves can simply watch a match in the French league and hope for plenty of goals.